1. Field of the Invention
The present invention relates generally to at least the field of medicine. More specifically, it relates to compositions and methods regarding triterpene-coated stents.
2. Description of Related Art
One of the leading causes of death in the developed world is coronary artery disease. Intravascular therapy has emerged as a frequent practice in lieu of surgical intervention. Non-surgical treatments include balloon angioplasty and the use of coronary artery stents. Whereas the incidence of restenosis after angioplasty approached 50%, the use of stents reduced the incidence to about 30% at six months.
A major recent advance, the introduction of drug-coated stents for local drug delivery, has been revolutionary, reducing the incidence of in-stent restenosis to 3-5%. In-stent restenosis is due at least in part to intimal hyperplasia resulting from vascular smooth muscle cell growth and migration. Shortly after deflation of the balloon during angioplasty, the coronary artery undergoes “elastic recoil” and initiates a clot formation. Initially, platelets are activated, leading to formation of thrombi. Injury to the vessel wall causes release of cytokines and growth factors that recruit inflammatory cells and stimulate the growth and migration of smooth muscle cells. A chronic inflammatory process is thus started. The use of anti-thrombotic, anti-inflammatory and growth-inhibiting drugs have been used to prevent restenosis.
The most active coated stents to date are two natural anticancer drugs, both of which possess immunosuppressive, anti-inflammatory, and growth-inhibiting (of smooth muscle cells) properties—Rapamycin (Johnson & Johnson; New Brunswick, N.J.) and Taxol (Boston Scientific; Natick, Mass.). Particular examples of coatings that have been described include WO 2004/012676, which describes a medical device having a bioactive agent crosslinked with a crosslinking agent, such as genipin. In a specific embodiment, the bioactive agent is a flavone/terpene lactone. Additionally, WO 00/10552 describes anti-angiogenic substances utilized as a stent coating, wherein the substance may be triterpene acids.
While the studies to date have furthered the use of stents in treatment of coronary artery disease, there is still a great need in the art for alternative reagents for coated stents having new therapeutic benefits.